1. Field of the Invention
The present invention relates to the field of display technology, and in particular to a thin-film transistor (TFT) array substrate structure.
2. The Related Arts
Liquid crystal displays (LCDs) have a variety of advantages, such as thin device body, low power consumption, and being free of radiation, and thus have wide applications, such as liquid crystal televisions, mobile phones, personal digital assistants (PDAs), digital cameras, computer monitors, and notebook computer screens, making them take a leading position in the field of flat panel displays.
Most of the LCDs that are currently available in the market are backlighting LCDs, which comprise a liquid crystal display panel and a backlight module. The working principle of the liquid crystal display panel is that liquid crystal molecules are filled between a thin-film transistor (TFT) array substrate and a color filter (CF) substrate and a drive voltage is applied to the two substrates to control a rotation direction of the liquid crystal molecules in order to refract out light emitting from the backlight module to generate an image.
The TFT array substrate comprises a plurality of gate lines and data lines. The plurality of gate lines and the plurality of data lines are perpendicular to each other to define a plurality of pixel units. Each of the pixel units comprises therein a TFT, a pixel electrode, and a storage capacitor. The TFT has a gate electrode that is connected to the gate lines, a source electrode that is connected to the data lines, and a drain electrode that is connected to the pixel electrode. When the gate lines are driven, the TFT is set in a conducting state so that a grayscale voltage signal that is fed through the corresponding data line is loaded into the pixel electrode, whereby a corresponding electric field is generated between the pixel electrode and a common electrode. The liquid crystal molecules contained in the liquid crystal layer is acted upon by the electric field to change direction thereby achieving displaying of various images.
The storage capacitor provides important functions of maintaining a voltage level and reducing division voltage of coupling capacitance in the TFT array substrate. An existing TFT array substrate is structured to form a storage capacitor by means of an overlapping portion between the common electrode and the pixel electrode. Such a storage capacitor has a relatively small capacitance that does not suit the needs of high quality display panels. On the other hand, increasing the capacitance of the storage capacitor by expanding the overlapping portion between the common electrode and the pixel electrode would lead to reduction of aperture ratio of the panel.
In addition, an existing TFT array substrate is structured to include multiple independent light-shielding layers in the form of blocks, which provide a sole function of shielding a channel zone of a semiconductor layer of the TFT to prevent performance deterioration of the TFT resulting from photogenerated carrier generated in the channel zone by photoelectric effect.